ajs writes: "The recent reporting on sea-level changes has often made the leap from observed rising sea-levels to predicted rises in sea-levels to so-called "doomsday" scenarios without a great deal of context. A recent article about rising antarctic sea levels on Scientific American's site has a fairly good discussion of the three different measures and how they relate. It also points out that observations currently map to the upper-end of the, "18-59 centimeters (7-23 inches) this century," predicted by the IPCC, but that the primary concern is that this could lead to a sudden melting of much larger amounts of inland ice, and could result in changes of meters (100 million people live within a meter of sea-level) that are not accounted for in current estimates."